The present invention relates generally to a correlation sample for scanning probe microscope and to a method of processing the sample, and, more particularly, to a correlation sample for a scanning probe microscope for use as a measurement standard while measuring a state of a surface of a sample, and to a method of processing the correlation sample.
In recent years, am irregular shape of the surface of a sample can be observed at an atomic level. That is, in an atomic force microscope for resolving atomic structure, a cantilever having a tip at the head portion thereof is used as a scanning probe. When the tip is scanned across the surface of a sample serving as a measured surface, attraction or reaction based on atomic forces between the surface of the sample and the tip are generated, and the atomic forces can be measured by detecting deflection of the cantilever.
The scanning probe microscope includes a magnetic force microscope for detecting a magnetic force of a measured surface developed by application of the above-mentioned atomic force microscope (hereinafter, AFM), a scanning Maxwell stress microscope for detecting voltage and electrostatic force of the measured surface, and a Kelvin probe force microscope, and each can detect a force which can not be obtained from the irregular data of the measured surface. The magnetic force microscope (hereinafter, MFM), the scanning Maxwell stress microscope (hereinafter, SMM), and the scanning Kelvin force microscope (hereinafter, KFM) can obtain the irregular data of the measured data in high resolution similarly to the AFM, and irregular data and magnetic image data can be observed in the same domain and at the same time in the MFM for example.
Therefore, when comparing the conventional measuring and observing method, the above-mentioned MFM, SMM, and KFM have various advantages such as high resolution, capability of observation of shapes of any surface at the same time, and ease of data acquisition. Therefore, the application field of these microscopes is spreading in domain analysis of magnetic media, analysis of magnetic material, analysis of electric characteristics and failure analysis of semiconductors, and estimation of work function in material.
However, although a relative comparing image of each force (N pole and S pole in magnetic force for example) can be obtained in the conventional scanning type probe microscope because of object of observation, there has been a problem in obtaining absolute strength (magnetic strength for example) because of the lack of a measurement standard.
A recent AFM is capable of measuring absolutely and is not limited only to observation by preparing a correlation sample of standard height. However, there has been a problem in that measured value varies at replacement of microscopes and samples because the sample is one kind and the measured surface is measured with respect to the sample used as a standard. No correlation sample of force performing as a standard has been prepared for MFM, SMM, and KFM performing as scanning probe microscope except for the above-mentioned AFM. Accurate detection of force of a measured surface using these microscopes requires measurement in a state in which distance between the measured surface and the tip is always kept constant. However, it is difficult to detect force distribution of a real correlation sample because the influence of irregularity appears in a measurement result when the surface is irregular even if a correlation sample is made. For example, an object (a magnetic body and the like) generating a force (a magnetic force, for example) serving as a certain standard is located at a surface of a silicon or glass substrate so as to make a correlation sample and is used for the correlation sample performing as a measurement standard of high density magnetic media. However, a real force distribution of the sample can not be measured accurately because it is difficult to accurately keep the distance between the tip and the surface of sample constant if measurement is attempted while moving the tip up and down so that the distance is kept constant.
For compensation of the above problem, it has been considered that the result of force measurement of a sample surface may be corrected based on irregular data of a correlation sample previously obtained. However, force measurement by the cancellation system is not in practical use yet so as to obtain an accurate measurement value.
The present invention has been made in view of the above-mentioned inconvenience in the prior art. A first object of the present invention is to provide a scanning probe microscope in which each force performing as a standard is accurately detected without influence of irregular data of surface and strength value of each force at measurement can be determined (absolute measurement) correlating the microscope using the detection and a method of processing the correlation sample. A second object of the present invention is to provide a scanning probe microscope in which absolute measurement can be accurately carried out based on the irregular data and a method of processing the correlation sample.
To achieve the above-mentioned objects, the present invention in a first aspect includes a correlation sample of a scanning probe microscope for measuring the state of a surface of a sample, comprising foreign domain where material having physical constant differing from material of a substrate is buried with certain thickness toward in-plane direction of the substrate performing as a sample, wherein surface of said substrate is flat.
As foreign domain where material having physical constant differing from material of a substrate is buried with constant thickness toward in-plane direction of the substrate performing as a sample and surface of the substrate is flat, the present invention is not influenced by irregular data, and can purely and correctly detect each force performing as a standard so as to be possible to carry out absolute measurement in various kinds of scanning probe microscopes. Here, a material having a physical constant differing from the material of the substrate means, for example, a magnetic body generating magnetic strength performing as a standard in the case of MFM and material generating voltage and electrostatic force performing as a standard. These materials are buried in the substrate with a certain thickness in order to obtain enough thickness to detect force depending on the materials because the materials could not detect force enough if thickness of buried material is thin.
The present invention in a second aspect includes a method of processing a correlation sample of a scanning probe microscope for measuring a state of a surface of a sample comprising steps of, forming holes of certain depth having a vertical wall face in the surface of a substrate at a predetermined domain of the substrate performing as a sample, burying material having a physical constant differing from material of the substrate into the holes formed in the forming process, and flattening the surface of the domain where the material differing in physical constant from the substrate is buried and the surface of the substrate.
According to the present invention, holes of a certain depth having a vertical wall face in the surface of a substrate at a predetermined domain of the substrate are formed, a material having a physical constant differing from the material of the substrate is buried in the holes, and the surface of the domain where the substrate is buried and the surface of the substrate are flattened. Therefore, the present invention is not influenced by irregular data, and can purely and correctly detect each force to perform as a standard so as to be possible to carry out absolute measurement in various kinds of scanning probe microscopes.
The present invention in a third aspect includes a correlation sample of a scanning probe microscope for measuring the state of a surface of a sample, comprising at least one of domains having a plurality of different height standards and a plurality of different width standards formed toward in-plane direction of the substrate performing as a sample.
According to the present invention, there is no need to worry about changing a measurement value if a sample or device is changed because absolute measurement can be carried out based on the result of comparing different standards (height or width) formed on the same sample as at least one of domains of plural different height standards and plural different width standards. Thus, by forming plural height standards and width standards comprising irregular data on the same sample, correct absolute measurement can be carried out. Here, the domain performing as height standards and width standard means that accurate holes and projection portions in size are formed toward in-plane direction of the substrate and distance between these bottom face, upper face, and side face is used as a standard.
The present invention in a forth aspect includes a method of processing a correlation sample of a scanning probe microscope for measuring the state of a surface of a sample comprising steps of, forming at least one of domains of a first height standard and a first width standard at a predetermined position of a substrate serving as a sample, and forming at least one of domains of a second height standard and a second width standard at position of substrate differing from the domain formed in the forming process.
According to the present invention, at least one of domains of a first height standard and a first width standard at a predetermined position of a substrate, and at least one of domains of a second height standard and a second width standard is formed at another position of substrate differing from the domain. Thus, as plural standards are formed at another process, the standard formed at former process does not receive influence at later process so as to form plural standards correctly. The present invention in a fifth aspect includes a correlation sample of a scanning probe microscope for measuring the state of a surface of a sample, comprising, foreign domain where material having physical constant differing from material of a substrate is buried with a constant thickness toward the in-plane direction of the substrate performing as a sample, and at least one domain of height standard and width standard formed at a position of the substrate differing from said foreign domain.
According to the present invention, as foreign domain where material having physical constant differing from material of a substrate is buried with a certain thickness toward the in-plane direction of the substrate performing as a sample, and at least one domain of height standard and width standard formed at position of the substrate differing from the foreign domain, physical value performing as a standard with one sample and at least one of height standard and width standard are taken at the same time as a standard value.
The present invention in a sixth aspect includes a method of processing a correlation sample of a scanning probe microscope for measuring the state of a surface of a sample comprising steps of, forming holes of a constant depth having a vertical wall face in the surface of a substrate at predetermined domain of the substrate performing as a sample, forming at least one hole of height standard and width standard at position of the substrate differing from the hole formed at said forming process, burying selectively a material having a physical constant differing from material of the substrate into the holes having said vertical wall face, and flattening the surface of domain where material differing in said physical constant from the said substrate is buried and the surface of said substrate.
According to the present invention, holes of a certain depth having a vertical wall face are formed in a surface of a substrate at a predetermined domain of the substrate, at least one hole of height standard and width standard is formed at a position of the substrate differing from that at which the hole is formed, a material having a physical constant differing from the material of the substrate is buried into the holes having the vertical wall face, and the surface of domain where material differing in the physical constant is buried and the surface of the substrate. Therefore, it is possible to form a physical constant performing as a sample and at least one of a height standard and a width standard are formed on one sample so as to take at the same time as a standard value.
The present invention in the seventh aspect includes a correlation sample of a scanning probe microscope according to any of the first aspect and the fifth aspect, wherein a coating film having surface wear and abrasion resistance is formed on the surface of the formed correlation sample.
According to the present invention, as a coating film having surface wear and abrasion resistance is formed on the surface of the correlation sample, the surface of the sample is protected from difference of friction force caused by difference of material of the substrate and material of the foreign domain, oxidation, corrosion, charging of the surface of the sample, adhesion of contaminant by charging up, flaw of surface and asymmetric wear by probe so as to keep flatness.
The present invention in an eighth embodiment includes a method of processing a correlation sample of scanning probe microscope according to any of the second aspect and the sixth aspect, further comprising the step of forming a coating film having surface wear and abrasion resistance on the surface of the formed correlation sample.
According to the present invention, as a process of coating film having surface wear and abrasion resistance on the surface of the correlation sample is added in any of the second aspect and the sixth aspect, surface of the sample is protected from difference of friction force caused by difference of material of the substrate and material of the foreign domain, oxidation, corrosion, charging up of surface of the sample, adhesion of contaminant by charging up, flaw of surface and asymmetric wear by probe so as to keep flatness.
The invention of the ninth aspect include a correlation sample of scanning probe microscope comprising, an electric resistor formed in a substrate of a certain section among surface of the substrate performing as a sample, and electrodes connected with said electric resistor at said surface of the substrate for letting current flow to the electric resistor.
According to the present invention, as an electric resistor is formed with certain depth from surface of the substrate in a substrate of a certain section among surface of the substrate, and electrodes are connected with the electric resistor at surface of the substrate for letting current flow, quantity of calorie of the electric resistor can be controlled depending on quantity of current flowing through the electrodes. Therefore, a correlation sample enable to heat locally for observing interaction of heat and image can be obtained.
The invention includes a method of processing a correlation sample of scanning probe microscope comprising steps of, forming an electric resistor in a certain section by covering except the certain section of surface of the substrate including semiconductor with ion implantation mask and by implanting impurity ion into certain domain in the substrate, and forming electrode material on at least two connecting portions connected with said electric resistor on said surface of substrate. According to the present invention, as the electric resistor is formed in a certain section by covering except the certain section of surface of the substrate including semiconductor with ion implantation mask and by implanting impurity ion into certain domain in the substrate, and the electrical resistor and material of electrodes are connected with at least two contacting portions, quantity of calorie of the electric resistor can be controlled depending on quantity of current flowing through the electrodes from the electrodes. Therefore, a correlation sample enable to heat locally for observing interaction of heat and image can be obtained.